Rep. Trey Gowdy, who chairs the House Oversight Committee and is a member of the House Intelligence Committee that Nunes heads, appeared on CBS’s “Face the Nation” on Sunday to discuss the controversial memo. It claims that top law-enforcement officials acted improperly when signing off on the secret surveillance of a former Trump campaign adviser.

While Republicans have used the memo to discredit Robert Mueller’s investigation into Russian meddling in the 2016 election, Democrats have characterised the document as biased and accused Nunes of cherry-picking details to include in it.

“I’m sure the president is frustrated,” Gowdy said. “So I’m sure that that instructs some of what he said. I actually don’t think it is has any impact on the Russia probe for this reason.”

Trump tweeted on Saturday that the memo throws cold water on the investigation into his campaign’s possible collusion with the Russian government, and whether he obstructed justice, most notably in firing former FBI Director James Comey.

“This memo totally vindicates ‘Trump’ in probe,” the president tweeted. “But the Russian Witch Hunt goes on and on. Their was no Collusion and there was no Obstruction (the word now used because, after one year of looking endlessly and finding NOTHING, collusion is dead). This is an American disgrace!”

Standing firmly with investigators

Gowdy, who played a role in drafting the memo that Trump authorised for release on Friday, added that its claims about the dossier do not diminish the allegations against Trump and his campaign staff. The dossier reportedly laid out ties between the Trump campaign and Russia, and the memo claims the FBI used it as an excuse to surveil campaign associates.

“There is a Russia investigation without a dossier,” Gowdy said. “So to the extent the memo deals with the dossier and the FISA process, the dossier has nothing to do with the meeting at Trump Tower. The dossier has nothing to do with an email sent by Cambridge Analytica.”

The congressman also commented on allegations of obstruction of justice against Trump.

“It also doesn’t have anything to do with obstruction of justice. So there’s going to be a Russia probe, even without a dossier,” he said.

On Sunday, Gowdy also mentioned that he did not think Trump should fire Deputy Attorney General Rod Rosenstein for his role in the alleged misconduct detailed in the memo.

“I don’t judge people based on a single decision that they make throughout the course of an otherwise really stellar career,” he said.

Gowdy, who announced previously that he would not seek reelection in 2018, also opened up about his political career.

“My wife hates it when I say this, but I was a pretty good prosecutor, I think. But I’ve been a pretty lousy politician,” he said. “So I’ve done it for seven years. I’m really grateful for the opportunity to do it, but it’s time for me to – whatever time I’ve got left – I want to spend it in the justice system because that’s where my heart is.”